Do not require ApplicationBootstrap in index.php

refs #5638
fixes #5529
Do not set UTC in index.php

refs #5638
fixes #5530
Do not exit the application when the logger has errors logged during bootstrap and stop preference loading on every request

Only fatals should exit the application.
Preferences must be loaded only once after login.
Revert "Change setup behavior of the AuthenticationManager to a lazy approach"

This reverts commit 226eb4eded6aa098ad268edc8fba5ddec09b423b.

Conflicts:
	library/Icinga/Authentication/Manager.php

This fix is not appropriate

refs #5506
Fix PHP Fatal error:  Class 'Icinga\Authentication\Membership' not found in ManagerTest.php
The ErrorController must not require authentication